Is it considered redundant to title the legend using the word 'Legend'? When I was in school the chair of our Geography department said "The first sign of a bad cartographer is to add 'Legend' to your legend." as it insults the intelligent of the reader. And that it would be the same as labeling the title block "title block", or the north arrow "North Arrow". I have only been able to find very little documentation on the topic and have concluded that it is simply a preference of the cartographer. Within my company though people argue both sides passionately. What is your opinion? Any help ending our endless debate will be greatly appreciated!

Mapping Center Answer:

First, good question, for the reasons you included. I think titling a legend is redundant, and I find most folks agree. You could take one of Tufte's perspectives and argue that if the legend is obviously a legend, then a title is "chart junk".

I don't think it is the preference of the cartographer, though I can see the logic in your conclusion, but rather a sign of the experience of the cartographer and the level of thought that was put into making a map that might need to be a finely honed communication tool.

When the legend needs a title, i.e., it's not obviously a legend or a complete legend, a title that is specific is good. Many folks use "Key to Symbols" or "Key to Economic Symbols" (or whatever needed to be elucidated by including a legend in the first place).

While on the subject, that gets me to one of my pet peeves, which are legends that are redundant in the first place. When designing a map, as many of the symbols as possible should be self-evident as to what they represent. If that's the case, then there's no need for a legend, or to include those symbols in a legend. So, basically the idea is to be ruthlessly minimalistic about including anything on the map that is not critical to fulfilling the map's communication mission. Thus, since titles by their nature verily scream to be read, they are an inherent distraction when placed on subsidiary information like legends.

There is actually some literature out there, primarily in cartography textbooks, on the way that legends and other map elements should be designed. Slocum et al. (2005) give legends a commendable amount of attention and there are various graphic examples. In addition, the Dent (1999) cart textbook has the advantage of providing instruction on legends for various types of thematic maps (e.g., choropleth, dot density, isarithmic maps, and more). There are now newer editions for both the Slocum and Dent cart textbooks.

In addition, we presented some guidelines on legend design in our presentation at the ESRI User Conference this year. You can download the presentation from Mapping Center on the Other Resources page – it is called "The One Minute Cartographer". The bottom notes for the part of the presentation about legends is complete (I am still adding more content to other parts of the presentation).

In specific regard to your question about using the title “Legend”, it is always best to ask if anything you add to map helps your map reader – if it does not, it may actually degrade your map by drawing attention away from the important content and adding one more level of interpretation for the map reader. I'll soon post a blog entry on this as well.